Patent GB-1466337-A (GB)
Title: Apparatus for promoting healing processes
IPC: A61B17/58
Filed: 1974-03-22
Abstract: 1466337 Electromagnetically stimulating bone growth W KRAUS 22 March 1974 [23 March 1973] 12890/74 Heading A5R Apparatus for promoting healing comprises at least one coil 10, Fig. 1, for surrounding a part of the body, connected to a lowfrequency current source, and at least two opposed sheet-like electrodes 14 arranged within the coil or coils and connected to a low-frequency voltage source. Electrodes 14, e.g. of thin metal sheet, are insulated to prevent galvanic contact with the part of the body being treated. A function generator 18 may act as both sources to supply symmetrical or asymmetrical alternating current or voltage, optionally with a direct current component, or a pulsating current. The frequency may be adjustable in the range 1-100 Hz, with less than 20% harmonic content, and the wave form may be copied from a physiological variation, e.g. the systole, by suitable sensors applied to the body. Alternatively, wave forms may be derived from a loop of magnetic tape. Preferably the energy contents of the magnetic field of the coil, and of the electric field of the electrodes, are approximately equal, the magnetic field may lie between 20 and 200 gauss, and the electric field between 0.1 and 1 V/cm. Preferably the amplitudes and phase difference of the two supplies from the function generator 18 are adjustable, with the phase difference about 90. The phase difference may be produced by a delay member or a differentiating member. The magnetic field is preferably aligned parallel to the direct of blood flow, with the electric field at right angles to this. In another embodiment, Figure 2 (not shown), a number of flattened cylindrical coils (10a-f are jointed together and connected in series, and insulated electrodes (14a-f) are carried on the inner surface of each coil. In another embodiment, Figs. 3a and 3b, a marrow nail 22, for insertion into a broken bone, comprises a pick-up coil 24 on a ferrite core and two electrodes 14' on the surface of the marrow nail which are insulated from contact with the bone. Each electrode 14' is connected to a respective end of the coil 24. In use, a coil 10 connected to a function generator 18 is placed over the injured part so as to bring the marrow nail into a magnetic field. The voltage induced into the coil 24 passes to the insulated electrodes 14' so that an electric field is produced generally perpendicular to the magnetic field. In other arrangements the pick-up unit may comprise a rod-like body (32), Figs. 5 and 6 (not shown), which may be a fluoro-carbon polymer, containing a cylindrical coil which may have a magnetic core. The ends of the coil are connected to two electrodes (14a) of partly cylindrical form preferably with their surfaces insulated. Alternatively, Fig. 6 (not shown), the electrodes (14b) may be annular and spaced axially. In another embodiment, Fig. 4 (not shown), a fractured bone (20) is fixed by a plaster casing in which two electrodes (14) are embedded connected to a function generator (18'). The injured part is surrounded by a coil (10) also connected to the generator (18') which is synchronised by a pulse receiving means (30) which may be a pressure sensor or a very low frequency microphone (M). The generator (18') may comprise current and voltage amplifiers, supplying respectively the coil and the electrodes, and an adjustable phase shifting device.